Intratumoral Cavrotolimod Combined With Pembrolizumab or Cemiplimab in Patients With Merkel Cell Carcinoma, Cutaneous Squamous Cell Carcinoma, or Other Advanced Solid Tumors

This study will be conducted in 2 phases. Phase 1 evaluates cavrotolimod given in combination with pembrolizumab in patients with advanced solid tumors in a classical 3+3 dose escalation design, with up to five ascending dose cohorts of cavrotolimod and enrollment of at least 3 patients per cohort to identify an RP2D. Patients will be dosed twice with cavrotolimod as a monotherapy before adding pembrolizumab, which will be added starting at the second cycle. Once the MTD or highest escalation cohort has been reached, or notable efficacy has been observed at a given dose level, and a decision as to a RP2D has been made, a two 2-stage expansion cohort design will be initiated. Phase 2 will evaluate the RP2D of cavrotolimod given in combination with pembrolizumab or cemiplimab in two expansion cohorts following a modified Simon 2-stage optimal design comprised of patients with Merkel cell carcinoma or cutaneous squamous cell carcinoma. who previously received and have progressed on an anti-PD-(L)1 CPI. Patients in the Merkel Cell Carcinoma cohort will receive IT cavrotolimod combined with a fixed, standard dose of pembrolizumab while the Cutaneous Squamous Cell Carcinoma cohort will receive IT cavrotolimod combined with a fixed, standard dose of cemiplimab. Phase 2 will include an exploratory expansion cohort to evaluate cavrotolimod in combination with pembrolizumab in patients with other advanced solid tumors, including melanoma, who have progressed on anti-PD-(L)1 therapy. Exploratory expansion cohorts will evaluate patients with melanoma and additional patients with Merkel Cell Carcinoma who do not meet criteria for enrollment in the primary Merkel Cell Carcinoma cohort. In addition, two exploratory cohorts have been added to evaluate patients with advanced solid tumors and no superficial tumor accessible for IT injection using subcutaneously administered cavrotolimod or IT injection into liver metastases. A cohort of up to 10 evaluable patients with locally advanced or metastatic solid tumors with no cutaneous, subcutaneous, or accessible nodal tumor lesions available for IT injection may be enrolled (inclusion criterion #4). The inclusion/exclusion criteria for this exploratory cohort will otherwise be the same as those used for the Phase 2 dose expansion cohorts except these patients will not be required to have a lesion accessible for biopsy (inclusion criterion #5). Patients will be dosed with cavrotolimod subcutaneously at a dose not to exceed the recommended Phase 2 dose, 32 mg, in combination with pembrolizumab.